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' application Bled August 95,

in all whom is may concern:

' Be it known that I, FRANK V. POOL? a citi zen of the United States, and a. resident ofNew nrnorrrcnaron forming part oi mm Patent No. asoszz. dated February as.

v 1885. ScrialNo. 17.71323 (No specimens) acid on uses'a loss' must be compensated for by the addition of a Jersey, have invented certain'new and useful Improvements in the Art of- Manufacturing I KitrdCellulose, of which the foilowing is a specification.

The invention relates to the art of menu factnringnhat: is known as soluble nitrocellulose, and especially to an improved pro-' cess of using nitrates in etl'ecting the restoration of the spent acids.

The process-has for 'itsobject particularly the removal of. the by product which is formed. .by thenctio'n of the sulphuric acid upon the l have discovered that the crystallh nitrate.

cation of this byproduct may be eifected and the crystallized parts .of the compound sepa- -lose as at present conducted in its most ape rated, the liquid being the part that is used in the conversion of the fiber.

The process of making soluble nitrocelluproved form' consists in, first, nitrating the fiberhy means of a bath of mixed acids, second, clarifying or filtering the spent acids which have been used to accomplish the nitration of the fiber, and, third, restoring the strength of the clarified spent acid by the dition of nitric and sulphuric acid.

In practice I. take-any given quantity of spent acid, enough to supply a factory for any ada given period. Having collected the same in an appropriate vessel an analysis is made, whereby I ascertain the quantity ofnitric acid which is necessary to effect a restoration.

avingarrived at a knowledge of the propor-. 'tionot'nitrie acid thatis demandedl add such decomposition of the nitrate by the sulphuric quantity of a nit-rate, either metallic, earthy, or 49' ofthe latter, and this loss which may be hastened by artificial means, if desired. Whenthe crystallizationhas been arated by any of the wellknow-n methods of then utilized in the treatment of the fiber.

It is.not to be understoodthat the'process described is limited to cases u here both clarification and restoration are demanded, as there vmay v dit ion of the cellulose that is used, the spent acid will contain but little floccnlent matter. and will not therefore require to beclarified or filtered.

to secure by Letters Patent, is

In the art of manufacturing nitrocellulose, the process herein described of restoring and purifying a spent bath, consisting in restoring of a suitable'quaptity of sulphuric acid and .a nitrate, eifecting'the crystallization of the resulting byproduct, and finally removing the hwy-product, substantial! y as set forth.

York and State of New York, this 22d day of August. A. D. 1885. a I

j FRANK V. POOL...

Witnesses:

GEORGE Coon,

Calls. 0.. GILL.

effected, the liquid part of the mixture is sep.

accomplishing-that result; The liquid part is;

be instances where, by reasons of the con- \Vhat I claim as my invention, and desire the strength of the bath by the introduction Signcdat New York, in the county of New inbefore described, it is. allowed to stand u-ntil a'crystallizationof the byproduct takes place, 

